Agricultural implement having diverse hitch and gang operation modes

ABSTRACT

An agricultural implement ( 10 ) has front and rear gangs ( 12, 13 ) of rotatable tillage tools arranged to follow each other along a line of travel. The front and rear gangs ( 12, 13 ) are mounted to a main frame ( 21 F), which is mechanically linked to a hitch frame ( 22 ) by a self-leveling linkage system ( 32, 33 ). The linkage system ( 32, 33 ) includes a spring assembly ( 48 ) arranged to allow relative movement between the hitch frame ( 22 ) and the main frame ( 21 F) when the implement ( 10 ) is in a lowered field working position. The linkage system ( 32, 33 ) has a pivoting cam ( 41 ) for changing the field working preload of the spring assembly ( 48 ) to provide multiple hitch operation modes. The linkage system ( 32, 33 ) is arranged to make the main frame ( 21 F) level and the hitch frame ( 22 ) rigid relative to the main frame ( 21 F) when the implement ( 10 ) is in a raised position. The linkage system ( 32, 33 ) also includes an adjustable stop device ( 43 ) that limits upward hitch movement to provide multiple rear gang hitch operation modes.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/349,647 filed on Apr. 3, 2014, which was a Section 371 national phasefiling of International Application No. PCT/US12/69922 filed on Dec. 14,2012, and claims priority of U.S. Provisional Application No. 61/576,974filed on Dec. 16, 2011. The contents of these prior applications areincorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to tillage equipment, and inparticular, to agricultural implements having first and second gangs ofrotatable tillage tools arranged to follow each other along a line oftravel.

Description of the Related Art

Conventional tandem X-shaped disk harrows use a forward swept front gangconfiguration where the front disk blades throw the soil outward fromthe center, resulting in a downward and inward set of blade reactionforces to acquire higher soil penetration loads than the machine couldgenerate by its own weight. This system worked well for early generalpurpose disk harrows where the common disk blade diameter was 18″ to 22″and machine frames generating less than 150 pounds per blade.

With the increase in crop residue and the need for greater soilpenetration over the years, today's general purpose disk harrows now use24″ diameter blades with machine frames generating 200 plus pounds perblade. Consequently, with the added machine weight and increasedhorsepower of today's tractors, the forward swept gang configuration cangenerate unstable reaction forces at the wing hinge points that mayresult in frame buckling, outer end soil ridging, unlevel fieldperformance and high speed frame bounce. To help stabilize the frontwing gangs, wing gauge wheel assemblies have been added by manufacturesto dampen and prevent excessive unstable blade reaction forces. Forproper machine operation, the gauge wheel assemblies require constantadjustments for different soil conditions and different machineoperating depths. High speed frame bounce is usually caused by theharmonic action between the front gang's C-shank spring hangers and avery firm soil profile at speeds above 7 mph. The forward swept winggangs bite into the firm soil compressing the spring hangers which thenrecoil upward to allow the gangs to raise up slightly. The gangs bite inagain and recoil a little higher, over and over until the frame takes ona noticeable bounce as it traverses the field.

There is a need for a better gang configuration that provides stablereaction forces to prevent wing buckling and high speed frame bouncewhile eliminating the need for front wing gauge wheels. An invertedfront V-shaped gang with its apex pointed in the direction of travel hasbeen used successfully on a disk harrow frame for many years. Sometimesreferred to as a “diamond disk,” they have some advantages anddisadvantages over the conventional X-shaped disk harrows. One advantageis the ability to operate in floating hitch mode due to the stable,self-gauging nature of the front gangs. The blade reaction forces on aninverted front gang are outward instead of inward, providing stabletension across the front hinge line. Floating hitch operation modeprovides better disk harrow performance on fields with widely varyingterrain changes or rocky fields that need gang protection. Underdifferent field conditions, such as shallow seedbed preparation on lowsloped fields, the same tillage tool may work better in a moretraditional spring-biased hitch operation mode.

Another advantage of an inverted front gang arrangement is the abilityto maintain level field performance over a wide variety of operatingdepths, operating speeds and gang angle changes. The level performanceof an X-shaped disk harrow is very sensitive to any type of dynamic gangforce changes, resulting in the need to continually re-adjust thefront-to-rear level settings and/or front wing gauge wheel position. Aninverted front gang arrangement with stable blade reactions, can handlewide variations in dynamic gang force changes without the need forcontinuous level adjustments.

There are two main disadvantages of an inverted front gang arrangementover conventional X-shaped disk harrows. The weight distribution betweenthe center frame and the wing frames are polar opposites between the twodifferent gang arrangements. The X-shaped disk harrow has a shortfront-to-rear dimension for its center frame, and wing frames that aregenerally longer than the center frame. The longer wing frames helpdistribute the needed weight to the wings to balance out the averageweight per blade.

In contrast, the diamond-shaped disk harrow has a long front-to-rearcenter frame dimension, and wing frames that are generally shorter thanthe center frame. The center frame weight per blade will likely be muchhigher than the weight per blade of the wings causing the wings to notpenetrate as well as the center frame. Ideally, in order to balance theweight per blade by physical weight alone, weight would need to be addedto the wing sections along with some reduction in weight from the centerframe. By adding physical weight to the wings, the folded transportcenter of gravity will rise causing possible unsafe conditions onroadside inclines.

Another disadvantage of a symmetrical diamond-shaped gang arrangement isthe front center soil movement being thrown into each other causingplugging and/or not tilling the center line area. If the spacing betweenthe front left and right gangs is widened to prevent plugging, largerweeds at the center line will not be removed.

There is a need for an improved frame and gang arrangement thateliminates these disadvantages while adding diverse gang angle and hitchoperation modes, in an efficient compact economical design.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an agricultural tillageimplement with a versatile self-leveling spring-biased hitch mechanismthat offers multiple and diverse hitch operation modes to match thefield conditions at hand by changing simple and intuitive hand-operatedcontrols located at the front of the machine.

The primary purpose of the spring, or other elastic member, in aspring-biased hitch is to allow the hitch to deflect downward as neededwhen working over a mounded soil structure, such as a field terrace, orto allow the front of the machine to raise upward as needed during anencounter with an immovable field obstruction. On most X-shaped diskharrows, the hitch spring pressure is preset to a substantial workingforce and is not usually adjustable. On X-shaped disk harrows, thespring pressure is also used to help control the depth of the frontgangs in soft field conditions. On a straight gang machine or adiamond-shaped gang machine, the front gangs are not so dependent on apreset spring pressure, thus the spring pressure can be increased,decreased or reduced completely, under certain conditions, to providerigid hitch, rock protection or front gang floating hitch operationmodes, respectively.

A feature of the present invention is a spring-biased self-levelingmechanism that provides multiple hitch operation modes by changing quickand easy controls near the front of the machine.

One object of the present invention is to provide a self-levelingspring-biased hitch system with a quick and easy means to control ordeactivate the spring pressure setting affecting the front gang'soperation. This is done by varying the activation distance along thespring rod that engages the hitch bias spring. In other words, thissetting varies the amount of working spring pressure that can be appliedto the hitch. This feature provides a spring-biased self-levelingmechanism with multiple hitch operation modes that can be changed usingquick and easy controls near the front of the machine. The mode changesmay involve incremental settings or a continuous movement through arange of mode settings.

A pivoting cam mechanism is attached to the front of the spring rod tochange the activation distance which engages the spring as the machinelowers into field position. The cam provides four different incrementalhitch mode settings listed from the most spring pressure to the least,namely; Rigid, Spring, Rock and Float.

In Rigid mode, the cam or other varying device causes the spring to becompressed significantly as the machine lowers into field position whilestill providing enough spring travel left to prevent high hitchstresses. This spring pressure would be similar to that of an X-shapeddisk harrow. Field conditions for use in Rigid mode would include: Stonefree semi-level fields, with compaction zones that need to be cutthrough completely.

In Spring mode, the cam or other varying device causes the spring to becompressed normally as the machine lowers into field position. This modewould allow good all purpose hitch flexing while still having enoughspring pressure to hold the front gangs down while cutting throughcompacted zones. Field conditions for use in Spring mode would include:General all-purpose field conditions without large field obstructions.

In Rock mode, the cam or other varying device causes the spring to becompressed slightly as the machine lowers into field position. This modeis used for fields where rock protection is needed to protect the frontgangs from damage. Field conditions for use in Rock mode would include:Fields with many immovable rock or stump obstructions or fields withsemi-sharp terrain changes.

In Float mode, the cam or other varying device causes the spring to besubstantially loose as the machine lowers into field position. This modeis use for fields with sharp terrain changes and can be used to providea higher degree of rock protection. Field conditions for use in Floatmode would include: Any field where the front gangs self-gauging workingdepth is adequate and it is desirable for the machine to follow theterrain's elevation contour precisely, while minimizing gang damage fromfrequent field obstructions.

Another feature of the present invention is the ability to control therear gangs rigid and float operation modes independent of the frontgangs rigid and float modes. In rear gang rigid mode, the hitch is notallowed to flex upward very much as the machine traverses sharp terrainchanges. This is a common situation seen on X-shaped disk harrows. Asthe front of the disk harrow enters a very low depression such as aterrace channel, the front gangs will come out of the ground when theupward hitch flex is used up. On the present invention, the rear gangmode is changed from rigid to float or rock mode by moving a pin thatnormally limits the upward hitch movement. This allows the hitch to flexupward farther than in rigid mode. In rear gang float mode, the frontgangs can easily follow the deep contour changes as the machinetraverses uneven terrain. Rear gang rock mode is an intermediate settingbetween rigid and float modes that provides more upward hitch flex thanrigid mode, but less than float mode for use in rocky conditions.

Another feature of the present invention is the rotational engagement ofthe horizontal level bar and the hitch control linkage during the liftprocess, which returns the machine to the same level state regardless ofthe rear gang operation mode. The hitch control linkage is defined asthe combination of the vertical control link 35 and the hitch bar 34.This feature guarantees the proper machine level during transport andfield end row turning while also freeing up the mode operation pins andcontrols to allow quick and easy hitch operation mode changes. When therear gang setting is in rigid mode, the rear gang adjustment pin 43pushes the rocker control link 35 forward at a rate to make the machinecome up level. When the rear gang setting is not in rigid mode, themachine's front gang lift rate will be slower than the rear gang's liftrate until the level spacer tube 46 contacts the control link 35. As themachine is raised, the level spacer tube 46 pushes the rocker controllink 35 forward to accelerate the front gangs upward motion until themachine is level at the raised lift position. At the top of the liftstroke, the level spacer tube pushes the rocker control link beyond therigid pin position hole to allow pin position changes. An alternateself-level system is shown in FIG. 20 where the level bar 32 contactsthe rocker control link 35 at the top of the raised position to releasethe load on the rigid pin position as above. The raised load path 30L isthen transferred through point 30P by the rotational convergence of thelevel bar 32 and the vertical rocker control link 35.

Another feature of the present invention is the position and movement ofthe center ground transport wheels in relation to the hitch operationmodes. While in floating hitch operation mode, the towing vehicle willnot provide any depth control for the front gang. Therefore, themachine's depth gauging wheels must be positioned close to the center ofgravity of the machine to provide depth support to both the front andrear gangs. When the machine is raised for transport, the center wheelsneed to rotate rearward to generate safe positive tongue weight whilebalancing the weight of any rear attachments.

Another feature of the present invention is having the wing lift andwheel assemblies move in opposite directions relative to the centerwheel assemblies. The wing wheel assemblies are arranged to move thewing wheels rearward away from soil flow when the implement is loweredto its field working position, and to move the wing wheels forward tosupport both gangs when the implement is raised to its transportposition.

Another feature of the present invention is an agricultural implementwith angle adjustable gang assemblies for variable soil and residuedisturbance needs and versatile wing fold members that attach the wingsto the center frame. The wing hinge point needs to be as low as possibleto minimize the folded transport height and limit gang interferenceduring downward wing flex. It is also desirable to have the pivot pointsfor the ground support wheels in a low position below the frames togenerate more vertical wheel travel during lift axle rotation. The lowpivot generates an arc path that minimizes wheel interferences andallows the frames to be constructed shorter front to back. This alsoallows the hydraulic lift actuators to be nested inside the framestructure for a clean above frame appearance.

Another feature of the present invention is an efficient method to widenthe center ground transport wheel base to a width that will offset thehigher transport center of gravity without widening the center frame,while reducing center frame fold and transport stresses, allowing thecenter frame to be constructed lighter. For road transport safetyconsiderations it is desirable to have the center ground transportwheels as wide as possible to prevent steep roadside incline mishaps.The center rear fold member is affixed to the underside of the centerframe and contains the pivot point connections for the center groundtransport axle in a low position as mentioned above. The outermost liftaxle pivot points are located outside the main frame dimensions andclose to the wing fold hinges. This location provides a more efficienttransfer of wing weight to the center transport wheels during thefolding sequence and road transport. Bending stresses on the center foldmember are reduced due to the close proximity of the hinge while centerframe stresses are almost completely eliminated. The center groundtransport wheel base is widened, for safety considerations, withoutwidening the center frame or incurring high bending stresses on the liftaxle tube. The wing's fold members are also affixed to the underside ofthe wing frames in a like manner and contain low pivot point connectionsfor the wing lift axles.

The front center wing fold members are affixed to the underside of thecenter frame in a like manner and are arranged in a V-shapedconfiguration with an apex of the V-shape pointing in the direction oftravel to more efficiently carry the rearward and outward draft loadswhile providing convenient anchor attachment points for the front centergang angle adjustment system. This arrangement further reduces bendingstresses on the center fold members so they can be constructed lighterto help reduce the overall weight of the center section as needed tohelp equalize the weight per blade between frame sections as mentionedabove.

Variable gang angle settings for disk harrows are common in the priorart. More commonly found on offset disk harrows, gang angle changesallow the operator to vary the amount of soil and residue disturbance.Unfortunately, changing the gang angles on an X-shaped tandem diskharrow can upset the level performance of the machine. Any gang angledifferences from side to side or front to back may cause uneven pulling,outside ridging or center ridges and furrows. The sensitive nature ofthe forward swept gang arrangement with its unstable reaction forcesonly compounds the level performance issues associated with gang anglechanges. Most manufactures have eliminated any gang angle features ontandem disk harrows in favor of fixed gang angles that prevent most ofthe level performance problems. Some X-shaped vertical tillage toolshave been introduced that provide different gang angle settings to meetthe growing need for residue management tillage. The maximum angle ofmost of these machines have been limited to angles below 10 degrees dueto the unfavorable dynamic forces encountered with forward swept gangsincluding high speed frame bounce. There is a need and a desire for atool that can provide a wider range of changeable gang angle settingsfor different soil and residue disturbance needs that doesn't upset thelevel performance of the machine or create hard to control dynamic gangreactions.

Another feature of the present invention is a gang angling system thatprovides gang angle changes on the order of 18 to 20 degrees movementwith respect to the frames to better fulfill the needs of today'sprogressive farmer. Gang angles of 0 to 5 degrees provide a high speed,shallow working “true vertical” tillage action, while gang angles ofapproximately 5 to 18 degrees provide a high disturbance verticaltillage action, while gang angles of 16 to 20 degrees cause the tillagetool to have a medium to slow speed, deeper working disk harrow typeaction. The invention uses an improved gang bar design in which a hoopedcomponent is affixed to the top of the gang bar that slides along arigid bar attached to the frames during angle adjustments. This slidearrangement provides greater angle movement in a compact space and islocated above the gang bar to prevent any interferences between theslide bar and normal gang components such as scraper assemblies. Theslide arrangement shown includes a series of holes in the slide platewhich can be used to secure the gang bar with pins or bolts as asimpler, more course set of adjustments or be used as a backup in caseof an actuator failure. The holes shown are spaced for 5 degree angleadjustments and can also be used as a visual reference to the currentangle when setting the gangs with the manual screw actuator. The holepattern also includes a means to fix the gang bars at a zero degreeangle (i.e., straight) for machine configurations involving straightrunning rotating tillage tools, such as chopper gangs, aeration spiketools, or non-concave plain or wavy coulters.

Another feature of the present invention is a gang angling actuatorsystem that provides either individual manual screw gang adjustments orremotely operated hydraulic rephasing actuator adjustments. The twogangs on the front center frame can be linked together by a mechanicallink to move in unison with each other to allow adjustment by a singlemanual actuator or by a dual master-slave rephasing hydraulic system.The two gangs on the rear center frame can also be linked together by amechanical link to move in unison with each other to allow adjustment bya single manual actuator or by a hydraulic rephasing slave cylinder.

Another feature of the present invention is a front blade arrangementthat has an offset apex from the center line of the machine and afore-aft offset gang arrangement that allows a plug free overlappingarrangement.

Numerous other objects of the present invention will be apparent tothose skilled in this art from the following description wherein thereis shown and described exemplary embodiments of the present invention.As will be realized, the invention is capable of other differentembodiments, and its several details are capable of modification invarious obvious aspects without departing from the invention.Accordingly, the drawings and description should be regarded asillustrative in nature and not restrictive.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective front view of a three-section shallow workingtillage tool with gangs set at a 5 degree angle fitted with a soilconditioning attachment.

FIG. 2 is a partial perspective side view of a generic straight gangshallow working tillage tool encountering a field obstruction andshowing the resulting hitch reactions.

FIG. 3 is a perspective view of the self-leveling assembly mechanismshowing the hitch mode pin placements for the front and rear gangsettings.

FIG. 4 is an exploded view of the self-leveling, spring-biased hitchmechanism according to the present invention.

FIG. 5 is a cut away view of the self-leveling, spring-biased hitchmechanism in the raised lift position showing the rotational convergenceand load transfer between level bar 32 and rocker control link 35, beingtransferred through level spacer 46 and the resulting load path 30L.

FIG. 6 is a cut away view of the self-leveling, spring-biased hitchmechanism in the raised lift position showing the hitch mode cam 41 andrear gang mode adjustment pin 43 changeable positions.

FIG. 7 is a cut away view of the self-leveling, spring-biased hitchmechanism in floating hitch operation field mode showing the hitch bar34, rocker control link 35, spring rod 44 and hitch mode cam 41movements when the hitch flexes downward due to terrain changes or whenthe front gang encounters a field obstruction.

FIG. 8 is a cut away view of the self-leveling, spring-biased hitchmechanism in floating hitch operation field mode showing the hitch bar34 and rocker control link 35 movement when the hitch flexes upward dueto terrain changes or when the rear gang encounters a field obstruction.

FIG. 9 is a perspective rear view of a wide center three-section shallowworking tillage tool with gangs set at a 5 degree angle for low soildisturbance with dashed lines showing zero and 15 degree gang anglepositions followed by a soil conditioning attachment.

FIG. 10 is a plan view illustrating a blade and tire arrangement of adiamond-shaped disk harrow tillage tool with the gangs set at theirlowest angle for vertical tillage and dashed lines for maximum gangangles fitted with manual turnbuckle actuators.

FIG. 11 is a partial front wing perspective view of the gang bar angleadjustment actuator, gang pivot point and hooped component inside theslide plate assembly.

FIG. 12 is a partial front wing exploded view of the gang bar angleadjustment parts according to the present invention.

FIG. 13 is a partial rear wing exploded view of the gang bar angleadjustment parts according to the present invention.

FIG. 14 is a partial rear wing perspective underside view of the gangbar angle adjustment turnbuckle, gang pivot point and wing gangadjustment bar.

FIG. 15 is a plan view illustrating a blade and tire arrangement of adiamond-shaped disk harrow tillage tool with gangs at their highestangle for maximum soil disturbance showing dashed lines for theretracted actuator gang angle and fitted with a dual master-slavehydraulic rephasing actuator system.

FIG. 16 is a partial perspective plan view of the offset front centergang arrangement with connecting linkage and offset apex fitted with adual master-slave hydraulic rephasing actuator system with hose routingshown.

FIG. 17 is a partial perspective plan view of the rear center gangsshowing the gang bar connecting linkage system (gang angle actuatorremoved for clarity).

FIG. 18 is a partial perspective view of a shallow working tillage toolin folded transport position showing the lift axle connection to thefold member outside of the main center frame.

FIG. 19 is a partial perspective view of an alternative manual actuatorsystem that uses a commercial screw jack assembly with a side wind typehandle.

FIG. 20 is an alternate cut away view of the self-leveling,spring-biased hitch mechanism in the raised lift position showing therotational contact point 30P between level bar 32 and rocker controllink 35 and the resulting load path 30L.

FIG. 21 is a partial perspective view of an alternative hydraulicactuator arrangement that provides greater angle changes in a compactspace.

DETAILED DESCRIPTION OF THE INVENTION

An agricultural implement according to the present invention will now bedescribed in detail with reference to FIGS. 1 to 21 of the accompanyingdrawings.

A tillage implement 10 according to the present invention is shown inFIG. 1. The implement 10 has three sections, including a center section21 and first and second wing sections 25 connected to the center section21. Each of the sections 21, 25 has a main frame 21F, 25F, a front gang12 of rotatable tillage tools, and a rear gang 13 of rotatable tillagetools. The front and rear gangs 12, 13 are arranged in a substantiallytandem formation with the rear gang 13 following the front gang 12 alonga line of travel. The tillage tools on the rear gang 13 are arranged tolaterally return soil displaced by the tillage tools on the front gang12.

The front gang 12 on the center section 21 has a V-shaped configurationwith its apex A pointing in the direction of travel. The front gang 12on the wing sections is arranged generally as a continuation of theouter trailing ends of the V-shape of the front gang 12 on the centersection 21. The V-shaped configuration provides a clean cut and ridgefree outer end performance of the front gang 12 while preventing orminimizing high speed bounce.

In the embodiment illustrated in FIG. 10, the apex A of the front gang12 is offset slightly from the centerline C of the implement. In thisembodiment, the number of left and right front gang blades are unequalon each side of the implement 10. The long center gang is positionedfarther forward than the shorter gang to provide an overlapping bladearrangement with full soil cutout and plug free operation.

The rear gang 13 can be arranged in a straight configuration (i.e.,perpendicular to the direction of travel), as shown in FIG. 2 and thedashed lines in FIG. 9. Alternatively, the rear gang 13 can be arrangedin a V-shaped configuration with an apex of the V-shape pointingopposite to the direction of travel, as shown in FIGS. 10, 15 and 17.

The wing sections 25 are pivotally connected to opposite sides of thecenter section 21 by fold members 27C, 27W, as illustrated in FIGS. 1, 9and 16. The fold members 27C, 27W are located below the main frame 21F,25F and have wing hinge points 27 located below the main frame 21F, 25F.The fold members include an assembly of front center fold members 27Cattached below the main frame 21F of the center section 21. The frontcenter fold members 27C are arranged in a V-shaped configuration with anapex of the V-shape pointed in the direction of travel and the outertrailing ends of the V-shape located beyond the respective outer sidesof the main frame 21F of the center section 21.

A plurality of ground support wheels 14 are mounted to the main frame21F of the center section 21 by a center lift assembly. The center liftassembly includes a center lift axle 31C mounted for rotation about anaxis that extends perpendicular to the line of travel. The center liftaxle 31C is attached to the fold member 27C by lift axle attachmentspoints 31P positioned on the center fold member 27C, which are locatedbelow the main frame 21F. The center lift assembly also includeshydraulic lift actuators 31H connected to the center lift axle 31C forrotating the center lift axle 31C for raising and lowering the wheels14. The lift actuators 31H are positioned below a top of the main frame21F.

The center lift assembly is arranged to move the support wheels 14forward to a position near a center of gravity CG of the implement whenthe implement is lowered to its field working position, as illustratedin FIG. 10. As a result, the support wheels 14, 15 can be used toprovide floating hitch mode depth control to both the front and reargangs 12, 13 simultaneously. The center lift assembly is also arrangedto move the support wheels 14 rearward to a position behind the centerof gravity CG of the implement when the implement is raised to itstransport position to provide a safe positive tongue weight. The centerlift assembly is attached to the center fold members 27C, as illustratedin FIGS. 9 and 18, outside of the main frame 21F dimensions to provide amore stable and efficient transfer of wing weight to the support wheels14 of the center section 21.

In the embodiments illustrated in FIGS. 1 and 2, a hitch assembly 16 isconnected to the center section 21 for connecting the implement to atractor or towing vehicle 17. The hitch assembly 16 includes a hitchframe 22 mechanically linked to the ground support wheels 14 by aself-leveling linkage system. The linkage system functions to maintainthe implement level during transport and field end row turning, whilealso providing diverse front and rear gang operation modes.

The linkage system includes a level bar 32 that is pivotally connectedto and extends forward from a throw arm on the center lift axle 31C. Afront end of the level bar 32 is pivotally connected to an upper end ofa rocker link 33. A lower end of the rocker link 33 is pivotallyconnected to the main frame 21F. The level bar 32 is arranged to movegenerally in a fore and aft direction when the center lift axle 31C isrotated.

In the embodiments illustrated in FIGS. 1, 3 and 4, a control link 35 ispivotally connected between the hitch frame 22 and the main frame 21F.For example, the control link 35 can be connected to the main frame 21Fwith the same pin used to connect the lower end of the rocker link 33 tothe main frame 21F. The control link 35 is nested between opposite sidesof the rocker link 33 and can be pivoted independently of the rockerlink 33.

When the implement is raised, the level bar 32 is moved in a forwarddirection causing the rocker link 33 to pivot about its lower endconnection. As the level bar 32 is moved forward, a load transfer point30P (see FIG. 20) on the front end of the level bar 32 engages acorresponding load transfer point on the control link 35. As a result ofthe rotational interaction and direct engagement between the level bar32 and the control link 35, the hitch assembly 16 is held in a rigidcondition relative to the main frame 21F when the implement 10 israised. In similar embodiment(s) illustrated in FIGS. 4 to 6, the levelspacer tube 46 provides the load transfer means between the level bar 32and the control link 35. Control link rotational stop lugs 35A areprovided to engage the main frame member 21F if the implement becomestail heavy during transport. Thus, the implement 10 is placed in a rigidlevel state mode when the implement is raised, regardless of the springforce setting of the self-leveling linkage system, thereby ensuring thatthe implement remains stable and level during transport.

When the implement is lowered into its field working position, the levelbar 32 is retracted rearwardly, causing the load transfer point 30P tomove out of engagement with the control link 35. As a result, the hitchassembly 16 can be automatically moved out of its rigid level state andinto one of its selected hitch operation modes as the implement islowered.

A spring assembly is arranged to allow relative movement between thehitch frame 22 and the main frame 21F when the implement 10 is in alowered field working position, and to be deactivated when the implement10 is in a raised position. The spring assembly includes a hitch biascompression spring 48 and a level spacer tube 46. Although the spring 48is illustrated in the drawings as a coiled spring, the term “spring” asused in this application is intended to cover other elastic members,such as solid rubber members or pneumatic springs or the like. Likewise,the term “spring rod” as used in this application is intended to alsocover a mechanical outer structure encasing a solid rubber elasticmember or the like.

The spring assembly also includes a spring rod 44 extending through acenter of the spring 48 and the level spacer tube 46, a washer 49 andlock nut 50 placed on one end of the spring rod 44, and a washer 45 andcam assembly 41 on the other end of the spring rod 44. The spring rod 44extends through a control link ball joint 35B on the control link 35 anda flange on the level bar 32. The spring 48 is sandwiched between thewasher 49 and the rear side of the flange on the level bar 32, while thelevel spacer tube 46 is sandwiched between the front side of the flangeon the level bar 32 and the ball joint 35B. The upward and downwardmovement of the hitch assembly 16 and the reaction forces therefrom areillustrated in FIGS. 7 and 8.

The cam assembly 41 provides an adjusting means for varying the springworking preload on the hitch bias spring 48. The cam assembly includes acam member 41 pivotally mounted to a fixed structure on the forward endof the spring rod 44. A pin 42, such as a wire lock pin, can be insertedthrough an aligned cam selection hole 41S in the cam member 41 to lockthe cam member 41 in a selected position relative to the fixed structureon the spring rod 44. The cam member 41 has a plurality of cam faces,each of which is a different distance from the pivot point of the cammember 41. The cam member 41 can be rotated to place a selected one ofthe cam faces into engagement with the washer 45, thereby changing theactivation distance (i.e., the effective length) of the spring rod 44and varying the amount of spring working preload placed on the spring48.

For example, the cam member 41 can have four settings defined by fourdifferent cam faces, as illustrated in FIGS. 3 and 6. The first settingis a rigid mode in which the greatest amount of spring working preloadis placed on the spring 48. The second setting is a spring mode in whichless spring preload is placed on the spring 48. The third setting is arock mode in which still less spring preload is placed on the spring 48.The fourth setting is a float mode in which little or no spring workingpreload is placed on the spring 48. The spring assembly is compressedinto progressively lower spring preloads, or zero working preload in thecase of the float mode, as the cam member 41 is changed from the rigidmode to the spring mode to the rock mode to the float mode.

When the implement 10 is raised, the level bar 32 moves forward andreduces or completely removes the tension on the spring rod 44. As aresult, the cam member 41 can be easily rotated for adjustment to adifferent setting when the implement 10 is raised. As the implement 10is lowered from its raised position into its lowered position, thespring rod 44 engages the spring 48 again to apply the selected amountof spring working preload for the selected hitch operation mode.

The linkage system also includes a second adjustment means for adjustinga limit of upward hitch movement to provide a plurality of rear ganghitch operation modes. The second adjustment means includes anadjustment pin 43 that can be selectively placed in either of three setsof holes through the rocker link 33. The top set of holes 33F provide afloat hitch operation mode for the rear gang 13. When placed in the topset of holes 33F, the pin 43 remains out of the path of movement of thecontrol link 35, thereby allowing the control link 35 to pivot relativeto the rocker link 33 to provide a rear gang floating hitch operationmode. When placed in the lower set of holes 33R or 33K, the pin 43limits the upward hitch movement by placing an upper limit on therelative pivoting movement between the control link 35 and the rockerlink 33, thereby providing a rear gang rigid hitch operation mode.

In the embodiments illustrated in FIGS. 16 and 17, the front and reargangs 12, 13 of the implement 10 comprise gang bars 12G, 13G on whichthe tillage tools are mounted. The gang bars 12G, 13G are separate fromthe main frame 21F and are not hinged together. The gang bars 12G, 13Gare mounted below the main frame 21F using an assembly that allowsadjustment of the angle of the gang bars 12G, 13G relative to the mainframe 21F to accommodate variable soil and residue disturbance needs.

The gang bar mounting assembly, as illustrated in FIGS. 11 to 14,includes at least one and preferably two hooped components 12H, 13Hlocated on top of each of the gang bars 12G, 13G, and correspondingrigid slide adjustment bars 61B attached to the bottom of the main frame21F, 25F. The slide adjustment bars 61B are arranged to slide throughthe hooped components 12H, 13H to allow the angle of the gang bars 12G,13G to be adjusted. The hooped components 12H, 13H thus travel along therigid slide adjustment bars 61B during angle adjustments. Slide pins 61Pcan be inserted into aligned holes in the rigid slide adjustment bars61B to quickly and accurately establish a common angle setting for allof the gang bars 12G, 13G on the implement. Threaded fasteners extendbetween a pivot plate on the gang bar and a corresponding pivot plate onthe main frame and can be tightened to secure the gang bars in theiradjusted positions.

The gang bar angles can be adjusted to approximately 0 to 5 degrees tocause the tillage tools to have a high speed, shallow working “truevertical” tillage action. The gang bar angles can be adjusted toapproximately 5 to 18 degrees to cause the tillage tool to behave as ahigh disturbance vertical tillage tool. The gang bar angles can also beadjusted to approximately 16 to 20 degrees to cause the tillage tools tohave a medium to slow speed, deeper working disk harrow type action.

A mechanical screw device, such as a turnbuckle 55, can be attachedbetween the gang bar and the main frame to provide a manual adjustmentof the gang bar angle. Alternatively, a rephasing hydraulic actuatorsystem 57, as illustrated in FIGS. 15 to 17, can be used to provide aremote adjustment of the gang bar angle.

The front gang 12 of the center section 21 includes left and right frontcenter gangs, and the rear gang 13 of the center section 21 includesleft and right rear center gangs. The left and right front center gangscan be linked together by a mechanical link 56F to move in time witheach other when adjusting an angle of the front gang bars 12G relativeto the main frame 21F, 25F. Similarly, the left and right rear centergangs can be linked together by a mechanical link 56R to move in timewith each other when adjusting an angle of the rear gang bars 13Grelative to the main frame 21F, 25F.

While the invention has been specifically described in connection withspecific embodiments thereof, it is to be understood that this is by wayof illustration and not of limitation, and the scope of the appendedclaims should be construed as broadly as the prior art will permit.

REFERENCE NUMERAL LIST

The following is a list of reference numerals used in the drawings ofthis application, along with the name of the labeled part:

A Apex

CG Center of gravity

C Center line

T Hydraulic Tee

10 FIG. 1 Three-section shallow working implement

10 FIG. 2 Generic shallow working implement

10 FIG. 9 Wide center shallow working implement

10 FIG. 10 Variable gang angle disk harrow

10 FIG. 15 Variable gang angle disk harrow

12 Front gang assembly

12G Front gang bar tube

12A Front gang anchor

12P Front gang pivot point

12H Front gang hooped component

12Z Front gang zero angle

12M Front gang max angle

12R Front gang angle retract position

13 Rear gang assembly

13G Rear gang bar tube

13A Rear gang anchor

13P Rear gang pivot point

13H Rear gang hooped component

13Z Rear gang zero angle

13M Rear gang max angle

13R Rear gang angle retract position

14 Center depth gauging wheels

15 Wing depth gauging wheels

16 Hitch assembly

16D Hitch downward movement

16U Hitch upward movement

17 Tractor or Towing vehicle

18 Field Obstruction

18R Obstruction reaction

21 Center frame section

21F Center frame

21S Center slide plate

22 Tongue

23 Hitch coupler

24 Pivot pins

25 Wing section

25A Wing gang adjustment anchor

25F Wing frame

25S Wing slide plate

25P Wing gang pivot plate

27 Pivot connections

27H Hydraulic actuators

27C Fold member (center)

27W Fold member (wing)

27A Gang adjustment anchor

27V Front center fold member

29 Soil conditioning attachment

30 Self level assembly

30L Raised Load Path

30P Load transfer point

30U Upward movement or Upward reaction

30D Downward movement or Downward reaction

31C Center lift axle

31P Lift axle pivot point

31H Hydraulic lift actuator

32 Level bar

33 Rocker link

33R Rear gang rigid pin position

33F Rear gang float pin position

33K Rear gang rock pin position

33S Rocker link stop rod

34 Hitch bar

34A Hitch height adjustment

34U Hitch bar upward movement

34D Hitch bar downward movement

35 Rocker control link

35B Control link ball joint

41 Hitch mode cam

41S Cam selection hole

42 Wire lock pin

43 Rear gang mode adjustment pin

43A Adjustment pin keeper

44 Spring rod

45 Cam washer

46 Level spacer tube

47 Washer

48 Hitch bias spring

49 Washer

50 Lock nut

55 Gang turnbuckle

56F Front gang connecting link

56R Rear gang connecting link

57 Hydraulic actuator (slave)

57R Right hydraulic actuator (master)

57L Left hydraulic actuator (master)

58 Hydraulic hose

59 Wing gang adjustment bar

61B Slide adjustment bar

61S Slide spacers

61P Slide pins

71 Screw jack actuator

71A Screw jack adjustment motion

What is claimed is:
 1. An agricultural implement, comprising: front andrear gangs of rotatable tillage tools arranged to follow each otheralong a line of travel; a main frame with a plurality of ground supportwheels mechanically linked to a hitch frame by a self-leveling linkagesystem, said front and rear gangs being mounted to said main frame; aspring assembly arranged to allow relative movement between the hitchframe and the main frame when the implement is in a lowered fieldworking position; an adjustment mechanism arranged to adjust a fieldworking preload of said spring assembly to provide a plurality ofdiverse front gang hitch operation modes; and said self-leveling linkagesystem being arranged to make the main frame level and the hitch framerigid relative to the main frame when the implement is in a raisedposition regardless of the hitch operation mode.
 2. The implementaccording to claim 1, wherein said adjustment mechanism comprises adevice that can be moved to change an activation distance along a springrod to vary said field working preload of said spring assembly.
 3. Theimplement according to claim 2, wherein said adjustment mechanismcomprises a cam member that can be rotated to change said activationdistance along said spring rod to vary said field working preload ofsaid spring assembly.
 4. The implement according to claim 2, whereinsaid spring rod is arranged to engage a spring of said spring assemblyas the implement is lowered from said raised position into said loweredfield working position, and said spring rod is arranged to diminish saidfield working preload as the implement is moved from said loweredposition to said raised position.
 5. The implement according to claim 1,wherein said self-leveling linkage system comprises a level bar and ahitch control linkage that rotationally interact with each other as theimplement is raised.
 6. The implement according to claim 5, wherein saidlevel bar is connected to a center lift axle used to raise and lowersaid ground support wheels relative to said main frame, said level barbeing arranged to move generally in a fore and aft direction when saidcenter lift axle is rotated, and said hitch control linkage is pivotallyconnected to said hitch frame, whereby said level bar is arranged toengage said hitch control linkage when the implement is raised toprovide a rigid level state regardless of the hitch mode setting of saidspring assembly to provide implement leveling when the implement israised.
 7. The implement according to claim 1, wherein said diversehitch operation modes comprise at least a rigid mode, a spring mode, anda float mode, and wherein said spring assembly is compressed intoprogressively lower spring preloads as said diverse hitch operation modeis changed from said rigid mode into said float mode.
 8. The implementaccording to claim 1, wherein said self-leveling linkage system furthercomprises an adjustable stop device that limits upward hitch movement toprovide a plurality of rear gang hitch operation modes.
 9. The implementaccording to claim 8, wherein said self-leveling linkage system isarranged to automatically return the implement to a level state as theimplement is raised, regardless of the rear gang hitch operation mode,by rotational interaction of a level bar and a hitch control linkage,thus providing proper implement level during transport and field end rowturning while also freeing up the adjustable stop device to allow quickand easy changes to the rear gang hitch operation mode.
 10. Theimplement according to claim 1, wherein said ground support wheels aremounted to said main frame by a center lift assembly arranged to movethe support wheels forward to a position near a center of gravity of theimplement when the implement is lowered to its field working position toprovide floating hitch mode depth control to both the front and reargangs simultaneously, and to move the support wheels rearward to aposition behind the center of gravity of the implement when theimplement is raised to its transport position to provide safe positivetongue weight.
 11. The implement according to claim 1, where said frontgang is V-shaped with an apex of the V-shape pointing in a direction oftravel to provide a clean cut and ridge-free outer end performance ofthe front gang while preventing or minimizing high speed bounce.
 12. Theimplement according to claim 1, wherein said front and rear gangscomprise gang bars on which said tillage tools are mounted, said gangbars are separate from said main frame and are not hinged together, andsaid gang bars are adjustable to change an angle of said gang barsrelative to said main frame to accommodate variable soil and residuedisturbance needs.